package com.example.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.conditions.query.QueryChainWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.DTO.ScrollResult;
import com.example.DTO.UserDTO;
import com.example.common.Result;
import com.example.common.SystemConstants;
import com.example.domain.Blog;
import com.example.domain.Follow;
import com.example.domain.User;
import com.example.mapper.BlogMapper;
import com.example.service.BlogService;
import com.example.service.FollowService;
import com.example.service.UserService;
import com.example.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.example.common.RedisContants.BLOG_LIKED_KEY;
import static com.example.common.RedisContants.FEED_KEY;

/**
 * 达人探店
 *
 * @author 苦行修士
 * @description 针对表【tb_blog】的数据库操作Service实现
 * @createDate 2024-07-15 19:21:14
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog>
        implements BlogService {

    @Resource
    private UserService userService;

    @Resource
    private FollowService followService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    /**
     * 查询博客信息列表
     *
     * @param current
     * @return
     */
    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();

        // 查询blog有关用户，遍历
        //records.forEach(this::queryBlogUser);
        records.forEach(blog -> {
            //查博客中的用户
            this.queryBlogUser(blog);
            //查询用户是否点赞
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    /**
     * 查询单个的帖子信息
     *
     * @param id
     * @return
     */
    @Override
    public Result queryBlogById(long id) {
        //1、查询blog
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("博客不存在！");
        }
        //2、查询blog有关的用户
        queryBlogUser(blog);
        //3、查询blog是否被点赞
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    /**
     * 对帖子进行点赞
     * 将set集合改为Zset集合
     *
     * @param id
     */
    @Override
    public Result likeBlog(Long id) {
        //1、获取用户id
        Long userId = UserHolder.getUser().getId();
        //2、判断当前用户是否点赞
        String key = BLOG_LIKED_KEY + id;
        //Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());
        //将set集合改为Zset集合——实现点赞排行耪
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) {
            //3、如果没点赞，可以点赞
            //3.1、数据库点赞数+1，
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //3.2、保存用户到Redis集合中
            if (isSuccess) {
                //stringRedisTemplate.opsForSet().add(key, userId.toString());
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        } else {
            //4、如果已经点赞，取消点赞
            //4.1、数据库点赞数-1,把用户从Redis的set集合中移除
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //stringRedisTemplate.opsForSet().remove(key, userId.toString());
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
                return Result.ok("取消点赞");
            }
        }
        return Result.ok();
    }

    /**
     * 实现点赞排行耪
     *
     * @param id
     * @return
     */
    @Override
    public Result queryBlogLikes(long id) {
        String key = BLOG_LIKED_KEY + id;
        //1、查询top5(前5名)的点赞用户  zrange key 0 4
        Set<String> tops5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (tops5 == null || tops5.isEmpty()) {
            log.debug("Redis中没有点赞用户的数据");
            return Result.ok(Collections.emptyList());
        }
        /**
         * 将一个包含用户ID的列表转换为一个包含UserDTO对象的列表
         * 解析出其中的用户id
         * 根据用户id查询用户
         * 将查询到的用户转换为UserDTO对象
         * 收集所有UserDTO对象到一个列表中
         */
        //2、解析出其中的用户id
        List<Long> ids = tops5.stream().map(Long::valueOf).collect(Collectors.toList());
        //3、根据用户id查询用户   select ... from user where id in(10,7)
        /*List<UserDTO> userDTOS = userService.listByIds(ids)
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());*/
        /*
        //第二种写法，拆分
        List<User> users = userService.listByIds(ids);
        // 3. 将查询到的用户转换为UserDTO对象
        List<UserDTO> userDTOS = new ArrayList<>();
        for (User user : users) {
            UserDTO userDTO = new UserDTO();
            BeanUtil.copyProperties(user, userDTO);
            userDTOS.add(userDTO);
        }*/
        String idStr = StrUtil.join(",", ids);

        //3、根据用户id查询用户  select ... from user where id in(10,7) order by field(id,10,7);
        /*List<UserDTO> userDTOS = userService.query()
                .in("id",ids).last("ORDER BY FIELD(id,"+idStr+")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());*/

        // 1. 调用userService的query方法获取查询对象
        // 2. 使用in方法添加查询条件，筛选出id在ids列表中的用户
        QueryChainWrapper<User> query = userService.query().in("id", ids);
        // 3. 使用last方法添加排序条件，按照id的顺序排序
        String orderByClause = "ORDER BY FIELD(id, " + idStr + ")";
        query.last(orderByClause);
        // 4. 调用list方法执行查询，获取结果列表
        List<User> users = query.list();
        // 5. 将结果列表转换为UserDTO对象的列表
        List<UserDTO> userDTOS01 = new ArrayList<>();
        for (User user : users) {
            UserDTO userDTO = new UserDTO();
            BeanUtil.copyProperties(user, userDTO);
            userDTOS01.add(userDTO);
        }
        //4、返回
        return Result.ok(userDTOS01);
    }

    /**
     * 新增博客/帖子
     * 实现关注推送功能
     *
     * @param blog
     * @return
     */
    @Override
    public Result saveBlog(Blog blog) {
        // 1、获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 2、保存探店笔记
        boolean isSuccess = save(blog);
        if (!isSuccess) {
            log.debug("用户新增笔记失败！！！");
            return Result.fail("新增笔记失败！！！");
        }
        //todo 实现关注推送功能
        //3、根据关注的博主id查询笔记作者的所有粉丝 select * from tb_follow where follow_user_id=?
        List<Follow> follows = followService.query()
                .eq("follow_user_id", user.getId())
                .list();
        //4、推送笔记id给所有的粉丝
        for (Follow follow : follows) {
            //4.1、获取粉丝id
            Long userId = follow.getUserId();
            //4.2、推送
            String key = FEED_KEY + userId;
            stringRedisTemplate.opsForZSet()
                    .add(key, blog.getId().toString(), System.currentTimeMillis());
        }
        // 3、返回id
        return Result.ok(blog.getId());
    }

    /**
     * 滚动分页查询关注博主推送的帖子
     *
     * @param max    ：当前时间戳
     * @param offset ：偏移量
     * @return
     */
    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        //1、获取当前用户
        Long userId = UserHolder.getUser().getId();
        //2、查询收件箱—ZREVRANGEBYSCORE key Max Min LIMIT offset count
        String key = FEED_KEY + userId;
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        //非空判断
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        //3、解析blogId、minTime(时间戳score)、offset
        List<Long> ids = new ArrayList<>(typedTuples.size());
        long minTime = 0; // 2
        int os = 1; // 2
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) { // 5 4 4 2 2
            // 4.1.获取id
            ids.add(Long.valueOf(tuple.getValue()));
            // 4.2.获取分数(时间戳）
            long time = tuple.getScore().longValue();
            if (time == minTime) {
                os++;
            } else {
                minTime = time;
                os = 1;
            }
        }
        os = minTime == max ? os : os + offset;
        //4、根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();

        for (Blog blog : blogs) {
            // 5.1.查询blog有关的用户
            queryBlogUser(blog);
            // 5.2.查询blog是否被点赞
            isBlogLiked(blog);
        }

        // 6.封装并返回
        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);

        return Result.ok(r);
    }

    /**
     * 查询blog是否被点赞
     * 在查询帖子之前就需要先进行判断
     *
     * @param blog
     */
    private void isBlogLiked(Blog blog) {
        //1、获取用户id
        UserDTO user = UserHolder.getUser();
        //todo 可以解决用户未登录查询出现的空指针异常
        if (user == null) {
            //用户未登录,无需查询是否点赞
            return;
        }
        Long userId = user.getId();
        //2、判断当前用户是否点赞
        String key = BLOG_LIKED_KEY + blog.getId();
        //Boolean isMember = stringRedisTemplate.opsForSet().isMember(key, userId.toString());
        //通过Redis中ZSet的`score`方法判断该用户id是否存在。
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        //如果用户已点赞则isLike为true,若未点，则为false
        blog.setIsLike(score != null);
    }


    /**
     * 查询blog有关的用户
     * 从帖子中获取用户ID，然后获取到用户信息，将用户的头像和昵称设置给帖子
     *
     * @param blog
     */
    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }
}




